Monday 1 September 2014

August Ends Historical 10-Month Cold Streak in Winnipeg



     It's official, the cold streak has finally ended (for now)! At 0.5°C above the previous 30-year (1984-2013) average mean temperature of 18.7°C, August was the first month since September last year to finish warmer than the previous 30-year average. This 10-month cold streak from October 2013 to July 2014 was the 4th longest on record and the longest streak of its kind since an 11-month streak in 1887-1888. The following table summarizes the cold streak by showing how much each month deviated from the previous 30-year average. A list of notable events and stats are also included.

Month
Deviation from previous 30-year average mean temperature
Notable events
September 2013
+2.5
October 2013
-0.6

November 2013
-1.1
December 2013
-7.4
January 2014
-3.8
February 2014
-6.4
March 2014
-6.8
April 2014
-4.1
May 2014
-0.1

June 2014
-0.1

July 2014
-1.0
August 2014
+0.5


     Despite being slightly above normal, only 2 days reached 30°C in August, below the normal of 5 days. So far this year, we have seen 7 days over 30°C, below the normal of 13 days up to now.

Moist, stormy August


     With an average dew point temperature of 14.4°C, August 2014 had the 4th highest average dew point in August on record since 1953 and the highest since 2010 when the average dewpoint temperature was 14.9°C. 24 days saw dew point temperatures over 15°C, well above the normal of 18 days.

Thunderstorm near Warren, Mb, August 24
     Rainfall during the second half of the month was the biggest story of August. During the last 2 weeks of the month, generally 85 to 150 mm of rain fell over the Winnipeg area. The biggest rainfall events occurred on the 21st and 29th, associated with thunderstorm activity. On the 21st, a stationary storm over the city in the evening dumped 50-100 mm of rain from downtown to Whyte Ridge causing significant street and overland flooding. On the 29th, training thunderstorms in the morning south of the city dumped 50-100 mm of rain again, this time in the Niverville to Steinbach regions. Remarkably, much of this rain fell in just half an hour.

     In total, 104.4 mm of rain fell at the airport in August, the first wetter than normal August since 2010 and the 23rd wettest August since 1873. Higher totals fell in other areas, including: 110.7 mm in south St Vital, 137.2 mm in Charleswood, ~142 mm at The Forks and locally over 160 mm in the Lindenwoods area. There were also 6 thunderstorm days, bang on normal.

55 comments:

  1. Perimeter Shield working it's magic big time today. Thunderstorms have been dancing around Winnipeg especially to the west and southwest all afternoon and we have yet to see anything here. Unreal.

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    1. Not a very big day anyway. I'm calling today just a bonus day. Looks like south end might get hit with another one soon, already heard some thunder to the west.

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  2. Not bad for September... Decent cell just scraped the south end. Frequent rumbles of thunder and some flashes of lightning. Worst missed me here, so only got 0.5 mm. Could see obvious hail shafts on the storm to the south.. All I've heard of so far is pea-sized hail, but there definitely could have been larger locally.

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  3. I drove out to catch the storm ddint get it in time but we stopped along a dirt road south of the perimeter picked up some pea sized hail that fell there wasn't a lot but we were able to see the backside of the storm decent lightning and hail shafts with it. Me and my dad went out for a drive. decent for September. Any storms tomorrow?

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  4. Hi Jj We seem to be in that 5 year cycle going back to 2004 of peaking in precipitation 2004 2009 2014 And having extremely wet augusts as well.Take a look at Charleswoods records and or the airport.If there is as much of an increase this time between 2014 over 2009 as there was in 2009 over 2004 an Ark might come in handy. This time though do you think it is a good idea to leave the breeding pairs of mosquitos off? ∞

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    1. I'm not seeing that cycle personally. 2009 wasn't that rainy of a year or a summer compared to other years. 2005 and 2010 were far rainier. Strangely, I haven't noticed the mosquitoes much at all this year. I suppose the city's efforts have payed off!

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    2. Seems that 5 year cycle Works for 5 10 & 2015 Allthough AUGUST 2009 and 2004 were top ten coldest years.and August 2009 was The nineth consecutive colder than normal month. as well. Does that mean next year will be wetter? As in 2005 - 10 and 2015?

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    3. As reported by charleswood and other South Winnipeg sites (back then north winnipeg sites measuring rainfall were rare and the airport as usual missed (reporting? ) comparable rain to the west and south wpg sites which in some cases were reporting over 100 mm. (see robsobs stats and highlights 2009)

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  5. Another unsettled day today, similar to yesterday, with a chance of showers and thunderstorms this afternoon. Very similar highs as well, around 23-24°C.

    We'll start off fairly sunny tomorrow under a mix of sun and cloud, but clouds will increase later in the day. Should reach around 23°C or so again, assuming enough sunshine. Could stay cooler if we are cloudier. For tomorrow night and Thursday, a stronger low pressure is expected to affect us. However, there is uncertainty at this point how far north the system will be.... American models are further north while the GEM is further south. Nonetheless, showers AND thunderstorms look likely for the RRV, including Winnipeg, tomorrow late evening through the overnight. Wrap-around showers will then be possible in the afternoon. As for rainfall totals, they will depend highly on thunderstorm activity. 15 + mm possible if this storm activity does occur. We'll have a better idea of what will happen in tomorrow morning's updates.

    Cooler on Thursday as well, likely only reaching mid to high teens. Warming up slightly for Friday, reaching around 20°C.

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  6. Line of thunderstorm taking shape in the western RRV at this time. Looking good that Winnipeg should get something, at least some rain. Best risk southern part of the city. Certainly a good start to September so far storm-wise!

    Heavy rain and thunder main threats with storms here today. Could be some gusty winds and small hail as well... should stay sub-severe for the most part.

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  7. JJ, what's behind this rather surprisingly stormy start to September?

    Thanks, Anon

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  8. Wow that turned into quite the storm in southern and eastern parts of the city. Storm strengthened right before hitting the city. Torrents of rain again here in south St Vital with approximately 12 mm in 9 minutes here. 14.4 mm total. Wind might have caused a slight underestimation in my gauge, but it's hard to say for sure. Front yard of our neighbour's was under about an inch of water and large puddles everywhere. Not bad for September!

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    1. Picked up 21.3 mm just south of the U of M.. Just took a walk to Kings park, very swampy with some massive puddles. Very impressive for September.

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    2. Only 2 mm here at my place in Charleswood as the storm intensified to my east. Not that I'm complaining.. I had enough in August! :)

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    3. Looks like I got lucky as I was just on the edge of the heavier band. 14.4 mm at my place, but more like 8.4 mm at Scott's and 9.2 mm at Matt's closer to the Perimeter. Other amounts include:

      22 mm in Waverley West
      18 mm in Island Lakes
      7-12 mm in the North Kildonan area
      6 mm in Whyte Ridge
      4 mm at the airport
      2.5 mm at the U of W downtown
      2 mm in Westwood

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  9. Yeah, that was an impressive storm for September. I picked up 17.4 mm here at my place in Windsor Park. As JJ mentioned, the brief strong winds that accompanied that storm may caused an over estimation but hard to say though.

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  10. Periods of sun and cloud today, so daytime highs hard to forecast. Could reach 22-23°C if we get enough sun. Rainy night tonight likely with periods of rain overnight and morning tomorrow. Thunderstorms will be possible, but I am concerned that the main storm risk may stay to our south. 10-20 mm possible, maybe more if thunderstorms occur. Chance of showers, drizzle remains in the PM hours.

    A bit warmer on Friday with a high near 20°C. A cold front is expected to push through in the late afternoon or evening. Showers are possible with this. Some thunder is possible, but I am concerned that instability may be too marginal. Cooler behind the front on Saturday, likely only reaching mid to high teens at most. Warmer for Sunday and Monday with some 20°C days possible. Models hint at another more significant system for Tuesday-Wednesday which could bring more rain and possible storms. So far, a significant cool down looks possible behind the system.

    By the way, today will be the last update of the thundercast for the season as the old daily routine restarts tomorrow.

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  11. The long range is certainly not uplifting. Hate too say this folks but it looks like our warmer days are numbered. It does look like a major cooldown sometime next week will bring back the below normal regime with a rather chilly second half of September in the making.

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    1. It seems that paltry polar ice.melt at least the canadian side has peaked for the year in early sept and we could have a.much greater polar ice.cap than the last several years by the first of Nov. Bring on What ever happened to El Nino?

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  12. Thunderstorm risk not looking overly exciting for us tonight. Best risk in southwestern Manitoba and closer to the US border. Better risk for Winnipeg looks to be in the morning to early afternoon timeframe.

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  13. Rain to begin even later than previously thought, likely not until late this morning. Thunderstorms are looking very likely at this point with widespread thunderstorm activity currently taking place in southwestern Manitoba. A few showers likely to continue through the afternoon to possibly early evening as well. 5-15 mm possible in total today, but locally higher under thunderstorms. Even managing to get some sunshine this morning which is just a bonus!

    Sunnier tomorrow, but with increasing cloud in the afternoon as a cold front approaches. A shower or thunderstorm is possible with this front in the afternoon and early evening. With very low instability, don't expect anything too strong.

    Mix of sun and cloud on Saturday, leaning a bit toward the cloud. There may be another cold front again, but with little to no instability, I don't expect thunderstorm activity. An isolated shower is possible, but certainly not a washout of a day.

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  14. South end was the unlucky place to be this time 'round. Just a measly 1.0 mm at my place in south St Vital. Meanwhile, 10 mm at the airport, 8 mm in Charleswood, 13 mm at The Fork and 15 mm downtown at the U of W.

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  15. JJ, is there any possible that we will see a dry week this month? The start of September has been inconsistent after a series of heavy downpours from thunderstorms, which we've been dealing since the end of Folklorama, almost 3 weeks ago. When we had Folklorama, our weather was consistent, with thunderstorm hitting us only once on the morning of the 8th. Is the weekend going to be pleasant for Manyfest at the Legislative grounds?

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    1. Generally, tomorrow through to Sunday looks a little drier than we have seen of late, but a chance for brief rainfall remains. There is still the chance for a brief shower or thunderstorm tomorrow afternoon and early evening associated with a weak cold front. Thankfully, if we do get anything it should be in and out and not last terribly long. Very slight chance of a shower late on Saturday as well associated with another weak cold front, but the chance is lower than tomorrow's. Sunshine should dominate over cloud cover both Saturday and Sunday in general.

      As for temperatures, expect a high around 19-20°C tomorrow, 22-24°C Saturday and 23-25°C on Sunday.

      I am increasingly becoming concerned about next week's cool down, probably starting on Tuesday. Models are indicating this could potentially be a more lengthy cool down, and significant as well. Some of the coldest days could barely exceed 10°C. Concerns over our first frost of the season will likely begin to arise as well, bad news for farmers given a late growing season, especially in southwestern Manitoba. Here's hoping it doesn't turn out as bad as expected!

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  16. Yeah, i'm not liking the long range forecast at all. But that's 2014 for ya, Gotta say this probably the worst weather year i've ever seen. This cooldown looks pretty bad and unfortunately this looks like a long term regime.

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  17. JJ, I forgot to mention it's going to be pleasant on Sunday for the Banjo Bowl, that will take place at the IGF.

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  18. Line of thunderstorms about to hit the city once again, the 4th t-storm day of the month here in south St Vital. Torrential downpours and strong winds the main threats. Gusts to 50-60 km/h look possible, especially for south Winnipeg.

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  19. Strong wind gusts verified... Definitely some strong winds here in south St Vital but sub-severe. Estimating 50-70 km/h gusts. Close lightning strikes and big boomers, again, not bad for September. Rain not a major story with about 4 mm so far and still raining lightly.

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    1. Total 4.1 mm here. A random, brief, but strong outflow wind behind the storm ripped a branch off my tree, but overall winds appeared sub-severe.

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  20. St Vital Park saw much greater rain started before 4 and was torrential for a few minutes..Weather Bug mobile is showing more rain and lightning in Carman A d just south of st Adolphe on west side of river in last 5 minutes. Don

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  21. Looks like more thunderstorms are possible later.... Again, heavy rain and gusty winds look like main threats.

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  22. I'm been impressed more in the past week than I have all summer in regards to thunderstorms.

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  23. I'm in East St Paul, we got loads of hail here. So much that the ground was almost completely white! mostly marble sized,

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  24. Wow this has strangely been one stormy start to September. 4 thunderstorm days out of five days of the month passed, i'd say that's shockingly impressive.

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  25. It looks like June and July in September this week, as the start of the month in Winnipeg and Southern Manitoba dominated with thunderstorms beyond the Labour Day weekend. The bulk of storms that strikes are between May and September or October in rare cases, peaking in June, the city's wettest month and the middle of July. In rare cases, we had thunderstorms here as early as March, occurred recently in 2012 on the 19th and as late as December, most recently occurred in 1982 on the 2nd. I'm not used to this weather late in the year, as this month has more thunderstorms than May, June, July or August in 2014. Stay alerted because, we might get at least couple more between now and Thanksgiving. At some point this month, let's hope to get a dry week, especially the weekend, even a decent Thanksgiving long weekend next month.

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  26. JJ, with thunderstorms, occurring in Winnipeg to kick off September on a stormy note, I'm used to this in the Philippines, where storms occurring nearly daily in my hometown in Manila and it's immediate surroundings during the rainy season, running from the end of May to October or November, or even as late as December. When I was there, I saw a thunderstorm as early as January or even as late as December, around Christmastime. Thunderstorms doesn't only occur in the Philippines during the rainy season, but they can occur anytime of the year. As I mentioned, January, the earliest thunderstorm occurred in this province occurred on the evening of the 15th with snow and thunder dubbed as "thundersnow" or "winter thunderstorm" near Portage la Prairie, at the height of the mild weather at that time, but it didn't hit Winnipeg.

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  27. Can't believe I'm saying this this early in the season, but many models indicating the potential for a snowstorm in Alberta early next week, with snow possible in parts of Saskatchewan and central-northern Manitoba. Some models even showing 10-30 cm in parts of Alberta north of Calgary. No guarantee this will actually occur; there are some warmer scenarios out there. For anyone wondering, I'm highly doubtful we'll see any this far south in Manitoba however. It really is just too early in the season for us here in the RRV.

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    1. Yes, we'll likely be spared from any of the white stuff here in the RRV, but I wouldn't be surprised if higher elevations to the west (Riding Mtn, Turtle Mtn, etc) see some snow Tuesday night. It all depends how much of that moisture from the west can spread east into southern MB, but it will be cold enough to support snow at higher elevations if any precip does fall. At this time of year, elevation plays a critical role in determining who gets snow and who merely gets a cold rain or drizzle. Not unprecedented that snow has fallen over those higher spots this early. Awful we even have to talk about this already! It was 33.8C in Winnipeg a year ago today!

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  28. Today is looking cloudier than anticipated judging by visible satellite this morning. Looks quite cloudy with just a few sunny breaks at times. Hopefully some breaks in the cloud can develop so we can get more sunshine. Daytime highs difficult to predict as a result. If we stay quite cloudy, 19-21°C may be the high, but with more sun we could reach 22-23°C.

    I can't stress enough how much we need to enjoy Sunday and Monday while they last.... Nothing but sun tomorrow with a high around 23°C or so. A mix of sun and cloud on Monday. There is the potential for highs in the high 20's, possibly 26-28°C, on Monday if we get enough sunshine and the if cold front doesn't pass through too early. There is the potential for showers and thunderstorms as a low pressure system moves through southern Manitoba along the cold front. Any storm that develops could become severe. However, my main concern will be capping.

    MUCH, MUCH colder on Tuesday, possibly over 15°C colder. Only expecting a high around 11°C, a huge difference from possibly mid to high 20's on Monday. At this point, it appears the cool down could possibly last at least a week.

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    1. Unfortunately, models are trending more and more towards an earlier passage of the front on Monday. Depending on how early it passes, it could really ruin a nice day with falling temperatures in the afternoon.

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  29. Any chance it will pass and be warming up by say golfday I mean Wednesday?

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    1. Unfortunately, Wednesday looks like one of the coldest days of the week with a high only around 8-10°C, maybe 11°C if we're lucky. It will be quite cloudy as well and there could be some light shower activity or drizzle at times, especially closer to the lakes where I suspect there will likely be enhanced lake-effect cloud cover and drizzle activity this week. Thankfully, this cloud and drizzle activity however, will keep us from getting frost on Tuesday and Wednesday. Too early to say if we'll escape it again late in the week.

      For Wednesday, it will also be quite breezy out of the north-northeast at 25 to 35 km/h, gusting up to 50 km/h.

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    2. Thats the most discouraging golf forecast I've seen.W'bug golf forecast is "ideal golf weather". I think we need some of whatever they're smokin.

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    3. Thnx for clarifying that Jj I appreciate the work that goes into your site.

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  30. Seems models have been severely underestimating highs the last few days. We reached 25.3°C yesterday, some 3-5°C warmer than most forecasts were indicating. As a result, I've raised my forecast high for today all the way to 26°C in anticipation that today may be similar to yesterday. Nothing but sunshine as well.

    Tomorrow, the change begins. It will start fairly sunny, but with some scattered cloud in the morning, under a south-southwest breeze. Cold front looks to pass sometime around lunch to mid afternoon, causing temperatures to plummet in the afternoon. We should manage to reach somewhere around 20-23°C before the front passes and drops our temperatures. It will also become quite cloudy in the afternoon with a chance for showers. Unfortunately, it looks like the front will be passing through too early to get a decent chance for thunderstorms, and severe activity. Looks like the best risk will remain to our east and south.

    A dreadful Tuesday and Wednesday with highs around 11°C Tuesday and 8-10°C Wednesday. Cloudy skies will dominate and there will be some light showers and drizzle at times. Winds will be breezy from the north-northeast at 25-35 km/h or so and gusts up to 50 km/h.

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  31. JJ, any chances of that front slowing down? Please tell me good news....

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    1. The chance is always there, but it would REALLY have to slow down quite a bit for us to get a better storm chance. I wouldn't count on us getting any storm activity tomorrow.

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  32. ANON commented on Sept 04 at 10:54pm "jj I forgot to mention its going to be pleasant on Sunday for the Banjo Bowl" was accurate only about todays game but "Pleasant" might not describe how we felt at the end

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  33. Some decent storms just west of the city this morning... Likely producing some hail. Looks like the worst cell right now will miss the city, but we should still get something. Watch for temperatures to plummet this afternoon behind the front.

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  34. Although the cluster of storms just missed Winnipeg, I wonder how many expected that to develop this morning, probably nobody. Seems like some missed the boat on that one this morning including the models.

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    1. NAM and HRRR were hinting at some convection in last night's runs, but I think most of us didn't think it would actually be as big as it ended up.

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  35. Cold front is now passing through Winnipeg, so don't expect temperatures to rise anymore today. In fact, things should actually cool down, as already mentioned, this afternoon.

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  36. JJ, there appears to be some hints that warmer weather could be returning in the 2nd half of September. What are your thoughts on this?

    Thanks, Anon

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    1. It is encouraging that the NAEFS has shifted towards more normal to above normal conditions in a couple week from now: http://weather.gc.ca/ensemble/naefs/semaine2_combinee_e.html

      It is clear this cool down wont last but it's too early to say just how warm we will get later this month.

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  37. Still 83 in Grand Forks at this hour while there are frost warnings at the border for the next three mornings.

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